Crucible and like furnace.



A. C. IONIDES, JR.

CRUCIBLE AND LIKE FURNACE.

APPucAriou man OCT. 4. 1912.

1 1 38,482 Patented May 4, 1915.

11 P g 2i 1 i .4.

22.42. 7. hm W J Attorney:

ALEXANDER CONSTANTINE IONIDES, JEL, OF LONDON, ENGLAND.

CRUCIBLE AND LIKE FURNACE.

Specification of Letters Patent.

Patented May 4, 1915.

Application filed October 4, 1912. Serial No. 723,972.

To all whom it may concern Be it known that I, ALEXANDER CONSTAN- TINE IoNIDns,-Jr., a subject of the King of Great Britain and Ireland, and residing at 34- Porchester Terrace, in the county of London, England, have invented certain new and useful Improvements in and Relating to Crucible and like Furnaces, of which the following is a specification.

This invention relatesto the application of the method of combustion described in the British Patent No. 15455 of 1909, to crucible and like furnaces and particularly to those of the type working with small difference of pressure between the fuel inlets and the outlets for the products of combustion, its object being to improve the efficiency of such furnaces and to raise the temperature attainable in a given time.

According to the invention the furnace comprises in combination a combustion chamber, a crucible therein means for admitting to said chamber a combustible mixture in practically self-burning proportions, and means by which the resulting products of combustion are emitted into the atmosphere at a point below the combustion chamber.

In the furnace shown in cross sectional elevation in the accompanying drawing, the crucible, a, Is surrounded by an inner furplied with a combustible gaseous mixture such as a self-burning mixture of coal gas and air in as near as practicable the correct proportions for obtaining completecombustion without an excess of either constituent remaining over after such combustion, which may be effected with or without a flame, As such a mixture is thus capable of burning completely in the presence of its own prodnets of combustion without the addition of further air, said products are heated and consequently pass upward through the passage, d. The hottest products of combust on thus surround the crucible, a, and in passing upward displace the V preceding products downward through the passage, 6. By this continued action the removal of the products of combustion from the furnace is ef fected by downward displacement with only a small difference of pressure between the fuel inlet, 9, and the outlet through which the products are discharged. By this means, the gaseous fuel does not require to be supplied under great pressure, and as no further air is added to the fuel after the latter has passed through the burner, it is now possible, and indeed preferable, to make the sectional area of the discharge conduit equal to-that of the fuel inlet, 9.

In a furnace thus constructed, the productsof combustion pass through at a: speed which is most conducive to efficient heat transmission from the hot products of combustion to the furnace and crucible, the result being that a considerably higher temperature is obtained within the furnace in a shorter time than has hitherto been possible. i I

In order that the products of combustion in being thus exhausted or discharged in a downward direction may'not influence the furnace burner, 7, and possibly cause overheating in the latter with consequent back firing of the self-burning mixture, the products of combustion discharged through the annular outlet passage, 6, are usually allowed to pass into suitable flues arranged below the furnace, but at some distance from the burner.

According to the construction illustrated, the fines consist in a. closed chamber, h, on the outside of the upper wall of which the furnace is placed, and delivers its products of combustiontlirough the outlet passage, 6, and an annular opening, is, in said upper wall. From the chamber, 72,, the products are further displaced downward through suitable conduits, m, leading to a second'flue chamber," a, at some distance below the chamber, h. The'conduits, on, between the two chambers, it and a, conveniently consist, in three pipes, 29-, two of which are shown in the cross sectional drawing and each of which is screwed into the under wall of the upper chamber, h, and into the upper wall of the second chamber, a. There is thus provided a rigid support for the furnace and upper flue chamber, and the second chamber may if desired be suitably sup ported at a convenient height above the ground level by means of standards, 9. The

products of combustion having thus passed through the flues are displaced through an opening in the under side of the second chamber, a, and thence into a suitable exhaust pipe, r, the cross sectional area of which is preferably equal to that of the inlet, 9, by which the self-burning mixture is supplied to the furnace.

The preferable form of burner for use in such a furnace contains a number of small fuel passages the diameter of which should not exceed one-sixteenth of an inch, while their length will, of course, depend upon the material of which the burner is made, and also upon the position of the burner with respect to the exhausted products of combustion. Such a burner is that illustrated, which consists in two parts, f and s, the lower one of which rests upon the top of the second flue chamber, a, and serves as a re: ceiver for the incoming self-burning mixture, while the upper part contains the passages, t, by which the fuel is conducted from thereceiver, s, to they combustion space below the crucible, a. The upper part, 7, of; the burner, is usually in the form ofa solid cylinder of fire brick or other suitable material, and is so, placed that its lower end surface forms a cover for the receiver, .9,

in the lower part of the burner, while the upper end of the part, f, projecting through an opening in the walls of the upper flue chamber, it, supports the inner wall, 6, of the furnace. Suitable packings, u, are placed between the burner and the furnace and the first flue chamber respectively, in order to prevent conduction of'heat to the burner. If desired however, the burner part, may be of a non-conducting material at its upper end and of metal or the like at its lower end. lhe number of passages, t, in such a burner issuch that their total cross sectional area is substantially equal to that of the fuel inlet conduit, 9, and they are preferably so arranged as to converge toward the upper end of the burner in order that the flame of the combustible may be concentrated on the adjacentsurface of the crucible, while at the same time preventing downward radiation of heat from the crucible by way of the passages, t. A burner thus formed has a relatively large external surface exposed to a current of cold air, which continually fiows between the upper and lower flue chambers, it and a, and as the products of combustion from the furnacecannot influence the burner, there is less tendency for the latter to become overheated, while the provision of narrow fuel passages in the burner further insures that backfiring of the combustible mixture is avoided.

Practical tests of a furnace thus constructed have shown that cast iron is melted within twenty minutes when the furnace is being supplied with a mixture of coal gas of average calorific value and air at a pressure equivalent to only four inches of water column, and that under such conditions, no

back-firing of the mixture takes place. i

What I claim as my invention and desire to secure by Letters Patent is l. A metallurgical furnace comprising in combination a combustion chamber, a crucible therein, means for admitting to said chamber a combustible mixture in practically self-burning pro-portions, and a down wardl-y extending conduit having one endin said chamber and the other end opening into the atmosphere at a point below the rest of the apparatus, in order that the products of combustion shall be emitted into the atmosphere at; the lowest point of the apparatus.

2, A metallurgical furnace comprising in combination a combustion chamber, a crucible therein, means for admitting to said chamber a combustible mixture in practically self burning proportions, and means by which the resulting products-of combustion are emitted into the atmosphere at a point below the combustion chamber.

3. A metallurgical furnace comprising in combination an outer casing, an inner concentrically placed casing open at its upper end to connect the chamber therein with an annular passage between the two casings, a conduit passing through both casings to let for the products of combustion shall be situated at the lowest point of the apparatus. Intestimony 'whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ALEXANDEROONSTANTINE IONIDES, JR. l/Vitnesses 0 J W T CARL R. Loop. 1

Copies of this patentmay be obtained for five cents each by addressing the. Commissioner of Patents, Washington, 13. 0. 

